[PATCH Kernel v20 3/8] vfio iommu: Cache pgsize_bitmap in struct vfio_iommu

Kirti Wankhede
2020-05-14T21:11:24Z

Calculate and cache pgsize_bitmap when iommu->domain_list is updated
and iommu->external_domain is set for mdev device.
Add iommu->lock protection when cached pgsize_bitmap is accessed.

Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
---
drivers/vfio/vfio_iommu_type1.c | 88 +++++++++++++++++++++++------------------
1 file changed, 49 insertions(+), 39 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index fa735047b04d..de17787ffece 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -69,6 +69,7 @@ struct vfio_iommu {
struct rb_root dma_list;
struct blocking_notifier_head notifier;
unsigned int dma_avail;
+ uint64_t pgsize_bitmap;
bool v2;
bool nesting;
};
@@ -805,15 +806,14 @@ static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
iommu->dma_avail++;
}

-static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
+static void vfio_pgsize_bitmap(struct vfio_iommu *iommu)
{
struct vfio_domain *domain;
- unsigned long bitmap = ULONG_MAX;

- mutex_lock(&iommu->lock);
+ iommu->pgsize_bitmap = ULONG_MAX;
+
list_for_each_entry(domain, &iommu->domain_list, next)
- bitmap &= domain->domain->pgsize_bitmap;
- mutex_unlock(&iommu->lock);
+ iommu->pgsize_bitmap &= domain->domain->pgsize_bitmap;

/*
* In case the IOMMU supports page sizes smaller than PAGE_SIZE
@@ -823,12 +823,10 @@ static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
* granularity while iommu driver can use the sub-PAGE_SIZE size
* to map the buffer.
*/
- if (bitmap & ~PAGE_MASK) {
- bitmap &= PAGE_MASK;
- bitmap |= PAGE_SIZE;
+ if (iommu->pgsize_bitmap & ~PAGE_MASK) {
+ iommu->pgsize_bitmap &= PAGE_MASK;
+ iommu->pgsize_bitmap |= PAGE_SIZE;
}
-
- return bitmap;
}

static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
@@ -839,19 +837,28 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
size_t unmapped = 0;
int ret = 0, retries = 0;

- mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;
+ mutex_lock(&iommu->lock);
+
+ mask = ((uint64_t)1 << __ffs(iommu->pgsize_bitmap)) - 1;
+
+ if (unmap->iova & mask) {
+ ret = -EINVAL;
+ goto unlock;
+ }
+
+ if (!unmap->size || unmap->size & mask) {
+ ret = -EINVAL;
+ goto unlock;
+ }

- if (unmap->iova & mask)
- return -EINVAL;
- if (!unmap->size || unmap->size & mask)
- return -EINVAL;
if (unmap->iova + unmap->size - 1 < unmap->iova ||
- unmap->size > SIZE_MAX)
- return -EINVAL;
+ unmap->size > SIZE_MAX) {
+ ret = -EINVAL;
+ goto unlock;
+ }

WARN_ON(mask & PAGE_MASK);
again:
- mutex_lock(&iommu->lock);

/*
* vfio-iommu-type1 (v1) - User mappings were coalesced together to
@@ -930,6 +937,7 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
blocking_notifier_call_chain(&iommu->notifier,
VFIO_IOMMU_NOTIFY_DMA_UNMAP,
&nb_unmap);
+ mutex_lock(&iommu->lock);
goto again;
}
unmapped += dma->size;
@@ -1045,24 +1053,28 @@ static int vfio_dma_do_map(struct vfio_iommu *iommu,
if (map->size != size || map->vaddr != vaddr || map->iova != iova)
return -EINVAL;

- mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;
-
- WARN_ON(mask & PAGE_MASK);
-
/* READ/WRITE from device perspective */
if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
prot |= IOMMU_WRITE;
if (map->flags & VFIO_DMA_MAP_FLAG_READ)
prot |= IOMMU_READ;

- if (!prot || !size || (size | iova | vaddr) & mask)
- return -EINVAL;
+ mutex_lock(&iommu->lock);

- /* Don't allow IOVA or virtual address wrap */
- if (iova + size - 1 < iova || vaddr + size - 1 < vaddr)
- return -EINVAL;
+ mask = ((uint64_t)1 << __ffs(iommu->pgsize_bitmap)) - 1;

- mutex_lock(&iommu->lock);
+ WARN_ON(mask & PAGE_MASK);
+
+ if (!prot || !size || (size | iova | vaddr) & mask) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* Don't allow IOVA or virtual address wrap */
+ if (iova + size - 1 < iova || vaddr + size - 1 < vaddr) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }

if (vfio_find_dma(iommu, iova, size)) {
ret = -EEXIST;
@@ -1668,6 +1680,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
if (!iommu->external_domain) {
INIT_LIST_HEAD(&domain->group_list);
iommu->external_domain = domain;
+ vfio_pgsize_bitmap(iommu);
} else {
kfree(domain);
}
@@ -1793,6 +1806,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
}

list_add(&domain->next, &iommu->domain_list);
+ vfio_pgsize_bitmap(iommu);
done:
/* Delete the old one and insert new iova list */
vfio_iommu_iova_insert_copy(iommu, &iova_copy);
@@ -2004,6 +2018,7 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
list_del(&domain->next);
kfree(domain);
vfio_iommu_aper_expand(iommu, &iova_copy);
+ vfio_pgsize_bitmap(iommu);
}
break;
}
@@ -2136,8 +2151,6 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
size_t size;
int iovas = 0, i = 0, ret;

- mutex_lock(&iommu->lock);
-
list_for_each_entry(iova, &iommu->iova_list, list)
iovas++;

@@ -2146,17 +2159,14 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
* Return 0 as a container with a single mdev device
* will have an empty list
*/
- ret = 0;
- goto out_unlock;
+ return 0;
}

size = sizeof(*cap_iovas) + (iovas * sizeof(*cap_iovas->iova_ranges));

cap_iovas = kzalloc(size, GFP_KERNEL);
- if (!cap_iovas) {
- ret = -ENOMEM;
- goto out_unlock;
- }
+ if (!cap_iovas)
+ return -ENOMEM;

cap_iovas->nr_iovas = iovas;

@@ -2169,8 +2179,6 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
ret = vfio_iommu_iova_add_cap(caps, cap_iovas, size);

kfree(cap_iovas);
-out_unlock:
- mutex_unlock(&iommu->lock);
return ret;
}

@@ -2215,11 +2223,13 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
info.cap_offset = 0; /* output, no-recopy necessary */
}

+ mutex_lock(&iommu->lock);
info.flags = VFIO_IOMMU_INFO_PGSIZES;

- info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
+ info.iova_pgsizes = iommu->pgsize_bitmap;

ret = vfio_iommu_iova_build_caps(iommu, &caps);
+ mutex_unlock(&iommu->lock);
if (ret)
return ret;

--
2.7.0